If you are one of more than 14 million people scheduled for a colonoscopy this year, you now have several screening options, according to Connie D. Abbott (MSN, CRNP), Nurse Practitioner at The University of Alabama in Huntsville (UAH) Faculty Staff Clinic.
Abbott said colorectal cancer is the third most common cancer diagnosed in both men and women in the United States, and most colonoscopies are part of screening for colon cancer. According to the American Cancer Society (ACS), one in 22 men and one in 24 women are diagnosed with cancer in their lifetime. She noted too, that although the death rate from colorectal cancer has decreased over recent years due to better screening, detection and treatment options, the death rate among people less than 55 years of age has increased by about one percent per year between 2007 and 2016.
But, Abbott said, when it comes to people of color there is a warning about colonoscopy screenings. "The American College of Gastroenterology recommends that African-Americans start colorectal cancer screening at age 45 — rather than age 50 for people of average risk for the disease. African-Americans are at a higher risk for developing polyps and these growths are also located deeper in the colon." According to a recent ACS research study led by Stacey Fedewa, black patients had a 31 percent higher risk for interval colon cancer (CRC’s) than white patients. CRC’s occur after a negative screening test and can arise from missed lesions or the development of new tumors.
A greater misconception about the disease, Abbott said, is that many people believe colon cancer is hereditary. "In actuality, only about five percent of colorectal cancers have a hereditary component to them. This includes such syndromes as hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis. Many colorectal cancers, however, are genetic mutations acquired some time in a person’s lifetime. Therefore, the general population is at average risk for the development of colorectal cancer and should be screened," she added.
Abbott said a suspicious polyp is one that shows characteristics of either being cancerous or pre-cancerous. "Polyps are growths in the colon. Some are made up of certain tissue and others have a certain pattern to the way they look. Polyps are typically characterized as adenomas and can be tubular, villous, tubulovillous, sessile or serrated. Most polyps that are small (less than ½ inch) are less likely to be cancerous than larger ones. Once polyps are removed, the tissue is evaluated under a microscope for any kind of abnormal growth pattern," she added.
A healthy diet is important in avoiding colorectal cancer. "There is no real way to prevent colon cancer, but a healthy diet can lower your risk," said Abbott. "There is a direct link between obesity and several forms of cancer. Following a low-fat diet and maintaining a healthy weight can help decrease some cancer diagnoses. A diet high in fat and processed foods increase the incidence of colonic polyps and these have the potential to turn in to cancer later on," she said. "Increasing the amount fruits and vegetables in a daily diet can also help. Research is still ongoing but increased fiber intake in the form of whole grains has shown potential to help as well."
According to Abbott, there are two categories for colorectal cancer screening tests: cancer detection tests and cancer prevention tests. Cancer prevention tests are preferred over cancer detection tests.
Cancer prevention tests include the following:
- Colorectal endoscopy — Colonoscopy is still the screening method recommended for early detection of colorectal cancer. Not everyone likes it and the test is costly. It requires a "bowel prep" meaning a clear liquid diet followed by consuming a prep that will clean out the bowel using laxatives. An invasive procedure, it involves taking time off of work and transportation to and from the procedure due to sedation. The test is done at a hospital or outpatient facility and is not without some risks. The endoscopy provides direct visualization of the colon and rectum and should something be detected, it can be removed immediately and sent for testing. If the test is negative, then a repeat colonoscopy is done in 10 years. If a polyp is detected, a repeat colonoscopy is performed based on the characteristics of the polyps — usually in two to five years.
- Double-contrast barium enema — Formerly recommended as the alternative for those declining colonoscopy. This has since been replaced by the CT colonography.
- CT colonoscopy — Also known as CT colonography or a virtual colonoscopy, it replaces a colonoscopy. The test is recommended every five years.
- PillCam Colon 2 — This is the second generation of the PillCam. A small camera is ingested in a capsule and takes images of the colon. Although its sensitivity for detecting polyps was significantly improved from the original PillCam, its specificity was much lower because it had a high incidence of "false positives." Patients utilizing this also have to undergo a specific type of prep to clean the bowel to provide direct visualization. Currently not recommended as an alternative to colonoscopy, but rather as a complementary procedure when a colonoscopy is incomplete, contraindicated or the patient refuses. More research is needed before using as a test option.
Cancer Detection Tests include the following:
- Fecal Immunochemical Tests (FIT) — Preferred cancer detection test. This replaces the guaiac-based fecal occult blood testing. Diet and vitamins affected the old test. The patient takes home a small vial, collects a specimen from stool and returns it to the office for testing. It tests for blood in the stool and if positive, then a colonoscopy is recommended. This test is repeated yearly. This test is available free of charge at the UAH Faculty Staff Clinic.
- Blood test (referred to as liquid biopsy) — "Liquid Biopsy" is a blood test that detects DNA from a tumor or cancer cells. This test is still in development and is not perfected, but is gaining ground according to the ACS. More research is needed to determine applicability and value. Issues include being able to isolate specific DNA from other cell-free genes, and avoid "false alarms" as well as being able to decide where the cancer is occurring in the body. Cancer may be discovered early and not be visible by other means such as CT or colonoscopy.
For more information as well as comparison of all colorectal cancer screening/prevention testing and pros and cons of each, visit the American Cancer Society website at cancer.org
Sources
- Article references: American Cancer Society www.cancer.org/cancer/colon-rectal-cancer
- Colorectal Cancer Screening: Douglas K. Rex, MD, FACG1, David A. Johnson, MD, FACG1, Joseph C. Anderson, MD1, Phillip S. Schoenfeld, MD, MSEd, MSc (Epi), FACG1, Carol A. Burke, MD, FACG1 and John M. Inadomi, MD, FACG1
- Indiana University Medical Center, Gastroenterology, IU Hospital, Indianapolis, USA.
- Am J Gastroenterol 2009; 104:739–750; doi:10.1038/ajg.2009.104; published online 24 February 2009
- Received 21 October 2008; accepted 12 December 2008 American College of Gastroenterology www.gi.org/guideline/colorectal-cancer-screening
- Colorectal Cancer Facts and Figures 2017-2019; retrieved from American Cancer Society website at www.cancer.org